Recent studies of the effects of alcohol on human behavior indicate that the environment and the belief that one has consumed alcohol greatly influence ones social and emotional behavior. These situational and expectancy effects are difficult and, in some respects, impossible to control in human studies. Furthermore, to attribute behavioral changes to ethanol, one must know the blood concentration of ethanol when behavior is observed. Nonhuman primates offer culture-free models in which to study alcohol's effects on behavior and the opportunity to develop accurate models for estimating blood levels based on analyses of ethanol pharmacokinetics in the species studied. This project will develop a computer simulation model for estimating blood alcohol levels from consumption records, pharmacokinetic parameters, and blood alcohol assays determined in individual subjects outside the behavioral test setting. The model will be applied to an existing and extensive data base of voluntary alcohol consumption and behavior to study the relationship between blood alcohol concentrations and behavior in monkeys. Pharmacokinetic studies will be carried out in six adult male pigtail macaques (Macacanemestrina) to establish values of the parameters necessary to describe the Michaelis-Manten kinetics of alcohol eliminatin, the intersubject variability in those parameters, intrasubject variability over time, and parametric changes resulting from enzyme induction with chronic exposure to ethanol. The parameters will be determined for an additional six subjects, and for each subject a simulation model will be constructed to estimate his blood alcohol level during time intervals when behavior was recorded. Behavior observations for all 12 subjects, studied in social situations were group size and dominance status were varied, will be examined for systematic relationships to blood alcohol level as estimated by the model. Behavioral variables to be studied include levels of aggression, friendly interactions, social and nonsocial activity levels, and further alcohol consumption. This study will clarify the direct effects of alcohol on primate social behavior. To the extent that the results can be extrapolated to man, it will contribute to our understanding of behavioral consequences of alcohol abuse.